Sievi is a municipality of Finland. It is located in the province of Oulu and is part of the North Ostrobothnia region. The municipality has a populati…Sievi is a municipality of Finland. It is located in the province of Oulu and is part of the North Ostrobothnia region. The municipality has a population of 4,594 and covers an area of 800.55 square kilometres of which 13.55 km² is water. The population density is 5.84 inhabitants per square kilometre.